Adjusting distributions of the Health Utilities Index Mark 3 utility scores of health-related quality of life

The Health Utilities Index Mark 3 (HUI3) is a multi-dimensional, preference-based measure of health status and health-related quality of life (HRQoL). HUI3 scores correlate strongly with self-ratings of health status and functional disability and vary according to age, gender and occupation. In comparative studies relating to HRQoL, it is necessary to carry out adjusted comparison of the health status of the different groups, taking into account unbalanced distribution of confounding variables. This paper describes a stratification method to adjust the distributions of HUI3 scores. This method provides a graphical representation of adjusted distribution of HUI3, which can also be used to adjust other HRQoL scores. Cross-sectional data from the 1998/1999 National Population Health Survey (NPHS) in Canada were used to verify the proposed method. Male agriculture workers and male construction workers in Canada had quite different age distributions but similar HUI3 distributions. After adjusting the age distribution of the construction group to match the distribution of agriculture group, the mean HUI3 score of the former significantly decreased.